local Arguments = require('Module:Arguments')
local TableTools = require('Module:TableTools')

local p = {}

local function error(text)
	return '\n*' .. require('Module:Error').error{ text, tag = 'p' }
end 

local function str_split(inputstr, sep)
    local t = {}
    for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
		table.insert(t, str)
    end
    return t
end

local function is_integer(str) 
	if str:match("%D") then 
		return false
	end 
	return true
end

local function trim(s)
   return s:match("^%s*(.-)%s*$")
end

p.main = function(frame)
	local args = Arguments.getArgs(frame)
	local title = mw.title.getCurrentTitle()
	
	local lua_config, lua_err = invoke_lua_source(args, frame)
	local headContent = lua_config and lua_config.head_content or ''

	local isSilent = args.silent ~= nil or (lua_config and lua_config.silent ~= nil)
	local isPeriodic = args.interval ~= nil or (lua_config and lua_config.interval ~= nil)
	
	return headContent .. 
		(isSilent and '' or 
			"<div style='float: right; padding-left: 15px;'>" ..
			'[https://sdzerobot.toolforge.org/database-report?page='..mw.uri.encode(title.prefixedText)..' Update the table now]' ..
			'</div>' ..
			"<div style='margin-bottom: 5px; border-bottom: 3px solid #2F74D0; padding-right: 10px;'>" ..
			"This table is generated by querying the [[wikitech:Help:Toolforge/Database|database replica]] "..(isPeriodic and 'and is periodically updated' or '').." by [[User:SDZeroBot|a bot]].<br> " ..
			'<mark>Edits made within the table area will be removed on the next update!</mark>' ..
			'</div>')
		.. '[[Category:SDZeroBot database report subscriptions]]'
		.. (lua_err or validate(args))
end

function validate(args)
	
	-- sql param is required, except if the config is lua-generated
	if not args.sql and not args.lua_source then
		return error('Invalid config: required parameter "sql" is missing')
	end
	
	local deprecated_params = {
		['frequency'] = 'interval'
	}
	
	-- check for invalid parameters
	for param, _ in pairs(args) do
		if deprecated_params[param] ~= nil then
			return error(param .. ' is deprecated, please use ' .. deprecated_params[param] .. ' instead')
		end
		if not TableTools.inArray({
			'sql', 'wikilinks', 'excerpts', 'comments', 'widths', 'hide', 'silent',
			'table_style', 'table_class', 'remove_underscores', 'pagination', 'output_page',
			'max_pages', 'interval', 'row_template', 'skip_table', 'header_template',
			'footer_template', 'row_template_named_params', 'postprocess_js',
			'lua_source', 'lua_function'
		}, param) and not param:find('^lua_arg_') then
			return error('Unknown parameter "' .. param .. '" used, ignoring')
		end
	end
	
	-- check incompatible param combinations
	if not args.row_template then
		if args.skip_table then 
			return error('Invalid config: skip_table can only be used with row_template')
		end 
	end
	
	if args.output_page then
		if args.pagination then 
			return error('pagination and output_page cannot be used together; output_page will be ignored')
		end
		local t1 = mw.title.getCurrentTitle()
		local t2 = mw.title.new(args.output_page)
		if t1.namespace ~= t2.namespace or t2.text:find(t1.text..'/', 1, true) ~= 1 then
			return error('output_page must be a subpage of the current page')
		end
	end

	-- check wikilinks config
	if args.wikilinks then
		local configs = str_split(args.wikilinks, ',')
		for _, config in ipairs(configs) do
			local parts = str_split(trim(config), ':')
			local srcColNum = parts[1]
			if not is_integer(srcColNum) then
				return error('Invalid wikilink config: Non-numeral source column number: '..parts[1]..'. Will be ignored.')
			end
			local ns = parts[2]
			if ns and ns:match("^c?%d+$") == nil then 
				return error('Invalid namespace number "'.. ns..'" in wikilinks parameter: refer to [[WP:NS]] for namespace numbers, or use "cN" to take namespace number from column number N')
			end 
		end 
	end
	
	-- check excerpts config
	if args.excerpts then
		local configs = str_split(args.excerpts, ',')
		for _, config in ipairs(configs) do
			local parts = str_split(trim(config), ':')
			local srcColNum = parts[1]
			if not is_integer(srcColNum) then
				return error('Invalid excerpts config: Non-numeral source column number: '..parts[1]..'. Will be ignored.')
			end
			local dstColNum = parts[2]
			if dstColNum and not is_integer(dstColNum) then
				return error('Invalid excerpts config: Non-numeral destination column number: '..parts[2]..'. Will be ignored.')
			end
			local ns = parts[3]
			if ns and ns:match("^c?%d+$") == nil then 
				return error('Invalid namespace number "'.. ns..'" in excerpts parameter: refer to [[WP:NS]] for namespace numbers, or use "cN" to take namespace number from column number N')
			end 
			local charLimit = parts[4]
			if charLimit and not is_integer(charLimit) then 
				return error('Invalid excerpts config: Non-numeral in charLimit: '..parts[4]..'. Will be ignored.')
			end 
			local hardCharLimit = parts[5]
			if hardCharLimit and not is_integer(hardCharLimit) then 
				return error('Invalid excerpts config: Non-numeral in hardCharLimit: '..parts[5]..'. Will be ignored.')
			end 
		end 
	end
	
	-- check column numbers in widths param
	if args.widths then
		local configs = str_split(args.widths, ',')
		for _, config in ipairs(configs) do 
			local parts = str_split(trim(config), ':')
			local column = parts[1]
			if not is_integer(column) then
				return error('Invalid widths config: Non-numeral column number: '..parts[1]..'. Will be ignored.')
			end
		end 
	end
	
	-- check numeric configs
	if args.comments then
		local columns = str_split(args.comments, ',')
		for _, column in ipairs(columns) do
			if not is_integer(trim(column)) then
				return error('Invalid comments parameter: Non-numeral column number: '..column..'. Will be ignored.')
			end
		end
	end
	if args.remove_underscores then
		local columns = str_split(args.remove_underscores, ',')
		for _, column in ipairs(columns) do
			if not is_integer(trim(column)) then
				return error('Invalid remove_underscores parameter: Non-numeral column number: '..column..'. Will be ignored.')
			end
		end
	end
	if args.hide then
		local columns = str_split(args.hide, ',')
		for _, column in ipairs(columns) do
			if not is_integer(trim(column)) then
				return error('Invalid hide parameter: Non-numeral column number: '..column..'. Will be ignored.')
			end
		end
	end
	if args.pagination and not is_integer(args.pagination) then 
		return error('pagination should be an integer. Will be ignored.')
	end 
	if args.max_pages and not is_integer(args.max_pages) then
		return error('max_pages should be an integer. Will be ignored.')
	end 
	if args.interval and not is_integer(args.interval) then
		return error('interval should be an integer. Will be ignored.')
	end 
	if args.row_template_named_params and not args.row_template then
		return error('row_template_named_params is only applicable when row_template is used')
	end

	return ''
end

function invoke_lua_source(args, frame)
	if not args.lua_source then
		return nil, nil
	end 
	local module_title = mw.title.new(args.lua_source, 828)
	if module_title == nil or module_title.namespace ~= 828 then
		return nil, error('lua_source should be a valid Module title')
	end
	local module_name = module_title.text
	local lua_params = ''
	for key, val in pairs(args) do
		if key:find('^lua_arg_') then
			local argName = string.sub(key, string.len('lua_arg_') + 1)
			local argValue = val
			lua_params = lua_params .. '|'..argName..'='..argValue
		end
	end
	local invoke = '{{#invoke:'..module_name..'|'..(args.lua_function or 'main')..lua_params..'}}'
	
	local moduleOutput = frame:preprocess(invoke)
	
	-- FIXME: more robust error detection
	if moduleOutput:find('error') ~= nil then
		return nil, moduleOutput
	end
	
	if not moduleOutput:match('^{{') or not moduleOutput:match('}}$') then
		-- XXX: Module is returning something other than report:generate(), error out? 
		return {}, nil
	end
	local config = {}
	-- Parse the configuration text to extract parameter values
	for line in moduleOutput:gmatch("[^\n]+") do
		local param, value = line:match("^|([^=]+) = (.*)$")
		if param and value then
			value = trim(value)
			if value ~= "" and value ~= "nil" then
				config[param] = value
			end
		end
	end
	return config, nil
end

return p